In recent years, against the background of prevention of global warming, emission reduction of CO2 has been demanded. The reduction of CO2 in an automobile means an improvement in fuel consumption performance, and as one of the solutions, the development and commercial application of an electric vehicle (EV) or a hybrid electric vehicle (HEV) has been pursued.
Especially, functions requested for a rotating electrical machine mounted in a hybrid electric vehicle include idling stop at the time of vehicle stop, energy regeneration during deceleration running, torque assist during acceleration running, and the like, and the fuel consumption performance can be improved by realizing these.
As the rotating electrical machine for this, a motor generator is transversely mounted at the outside of an engine, a belt is stretched between the motor generator and a crank shaft pulley, and bidirectional driving force transmission is performed between the motor generator and the engine.
At the time of electric operation, DC power of a battery is converted into AC power by an inverter. This AC power is supplied to the motor generator, and the motor generator is rotation-driven. This rotation force is transmitted to the engine through the belt, and the engine is started. On the other hand, at the time of electric power generation, part of the driving force of the engine is transmitted to the motor generator through the belt, and AC power is generated. This AC power is converted into DC power by the inverter and is stored in the battery.
As this kind of conventional art, for example, patent document 1 or 2 discloses an inverter additionally provided at the outer periphery of a rotating electrical machine in a radial direction or at the end face thereof in an axial direction, and a cooling structure of the rotating electrical machine and the inverter by a cooling fan of the rotating electrical machine. However, there is no disclosure as to the sufficient size of the inverter device for exhibiting characteristics of the rotating electrical machine, measures to miniaturize the inverter for integral mounting, and the like.
Patent document 1: JP-A-11-122875 (paragraphs 0025 to 0034 and FIG. 1)
Patent document 2: JP-A-11-27903 (paragraphs 0013 to 0018 and FIG. 1)